John signed the Anne Frank Declaration - a copy of the decleration is below:

I pledge my support to:

Anne Frank is a symbol of the millions of innocent children who have been victims of
persecution. Anne’s life shows us what can happen when prejudice and hatred go unchallenged.
Because prejudice and hatred harm us all,

I declare that:
• I will stand up for what is right and speak out against what
is unfair and wrong
• I will try to defend those who cannot defend themselves
• I will strive for a world in which our differences will make no difference – a world in which everyone is treated fairly and has an equal chance in life.